* {
    margin: 0;
    padding: 0;
}

h3 {
    width: 1500px;
    height: 50px;
    text-align: center;
    line-height: 50px;
    border-bottom: 1px solid #ccc;
    margin: 20px auto;
}

.fill-mode {
    width: 1200px;
    box-shadow: 0 0 4px 0 #ccc;
    margin: 20px auto;
}

p {
    border-top: 1px solid #ccc;
    margin: 10px;
}

.box {
    width: 200px;
    height: 100px;
    background-color: #0ff;
    margin: 10px;
    animation: demo 7s linear 2s 1 normal running;
}

.none {
    animation-fill-mode: none;
}

.forwards {
    animation-fill-mode: forwards;
}

.backwards {
    animation-fill-mode: backwards;
}

.both {
    animation-fill-mode: both;
}

@keyframes demo {
    from {
        margin-left: 0;
        background-color: rgb(86, 122, 122);

    }

    to {
        margin-left: 1000px;
        background-color: #0f0;
    }
}

@-webkit-keyframes demo {
    from {
        margin-left: 0;
        background-color: #0ff;

    }

    to {
        margin-left: 1000px;
        background-color: #0f0;

    }
}